Re: [syzbot] [jfs?] KMSAN: uninit-value in txLock

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in txLock

ip: ffff8880139c57b8: 139c57b0 ffff8880 00000000 00000000
ip: ffff8880139c57c8: 00000000 00000000 00000000 00000000
ip: ffff8880139c57d8: 00000000 00000000
=====================================================
BUG: KMSAN: uninit-value in hex_dump_to_buffer+0xe86/0xeb0 lib/hexdump.c:172
 hex_dump_to_buffer+0xe86/0xeb0 lib/hexdump.c:172
 print_hex_dump+0x10d/0x330 lib/hexdump.c:277
 txLock+0xe8f/0x29d0 fs/jfs/jfs_txnmgr.c:832
 xtInsert+0xd25/0x1530 fs/jfs/jfs_xtree.c:645
 extAlloc+0x12ec/0x17e0 fs/jfs/jfs_extent.c:150
 jfs_get_block+0x610/0xe30 fs/jfs/inode.c:254
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x281f/0x6100 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3133 [inline]
 jfs_direct_IO+0x12b/0x3f0 fs/jfs/inode.c:339
 generic_file_direct_write+0x2bc/0x730 mm/filemap.c:4258
 __generic_file_write_iter+0x25b/0x460 mm/filemap.c:4427
 generic_file_write_iter+0x131/0x980 mm/filemap.c:4467
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 hex_dump_to_buffer+0xe7f/0xeb0 lib/hexdump.c:174
 print_hex_dump+0x10d/0x330 lib/hexdump.c:277
 txLock+0xe8f/0x29d0 fs/jfs/jfs_txnmgr.c:832
 xtInsert+0xd25/0x1530 fs/jfs/jfs_xtree.c:645
 extAlloc+0x12ec/0x17e0 fs/jfs/jfs_extent.c:150
 jfs_get_block+0x610/0xe30 fs/jfs/inode.c:254
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x281f/0x6100 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3133 [inline]
 jfs_direct_IO+0x12b/0x3f0 fs/jfs/inode.c:339
 generic_file_direct_write+0x2bc/0x730 mm/filemap.c:4258
 __generic_file_write_iter+0x25b/0x460 mm/filemap.c:4427
 generic_file_write_iter+0x131/0x980 mm/filemap.c:4467
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4576 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x373/0x1250 mm/slub.c:4905
 mempool_alloc_slab+0x36/0x50 mm/mempool.c:722
 mempool_alloc_noprof+0x19d/0x3c0 mm/mempool.c:566
 alloc_metapage fs/jfs/jfs_metapage.c:264 [inline]
 __get_metapage+0xa20/0x1840 fs/jfs/jfs_metapage.c:761
 xtSplitRoot+0x164/0x1560 fs/jfs/jfs_xtree.c:1242
 xtSplitUp+0x8c2/0x2ea0 fs/jfs/jfs_xtree.c:785
 xtInsert+0x77a/0x1530 fs/jfs/jfs_xtree.c:608
 extAlloc+0x12ec/0x17e0 fs/jfs/jfs_extent.c:150
 jfs_get_block+0x610/0xe30 fs/jfs/inode.c:254
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x281f/0x6100 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3133 [inline]
 jfs_direct_IO+0x12b/0x3f0 fs/jfs/inode.c:339
 generic_file_direct_write+0x2bc/0x730 mm/filemap.c:4258
 __generic_file_write_iter+0x25b/0x460 mm/filemap.c:4427
 generic_file_write_iter+0x131/0x980 mm/filemap.c:4467
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 6587 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
=====================================================


Tested on:

commit:         d662a710 Merge tag 'dmaengine-7.1-rc1' of git://git.ke..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=14daa4ce580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5aa0042346eface8
dashboard link: https://syzkaller.appspot.com/bug?extid=d3a57c32b9112d7b01ec
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=171624ce580000